When Slytherin departed Hogwarts, he left behind the Chamber of Secrets with the purpose of an heir opening the chamber one day and unleashing a means to 'protect' the school from those who, in his view, were unworthy to study to magic: Muggle-borns. The legacy of his feud with Gryffindor has continued in modern times with their two houses sharing the most intense rivalry at Hogwarts. Slytherin ultimately decided to leave the school when he was unable to persuade the other founders to join his side in their argument. According to the Sorting Hat, their dispute would erupt into a duel between the two former comrades or a civil war between their students.

Slytherin's opposition to allowing witches and wizards of Muggle heritage to enrol created great controversy at Hogwarts, and it became the root of a feud that would destroy his friendship with Godric Gryffindor.

Slytherin's views at the time could be attributed to the persecution of witches and wizards at the hand of Muggles during his era. Salazar Slytherin was a proponent of pure-blood supremacy who considered Muggleborns too untrustworthy to be taught magic. The colours also corresponded with waters around lakes and lochs often being green, and silver being often associated with grey rainwater. Others speculate that it was chosen to symbolise many Slytherins' hope for a pureblood-only wizarding society. Similarly, in Celtic mythology, water is seen as a portal to another world, leading some to believe that the element was chosen to symbolise a Slytherin's dream for a world in which their goals and ambitions had finally been achieved. Slytherin corresponded roughly with the element of water due to serpents being commonly associated with the sea and lochs in western European mythology, as well as serpents being physically fluid and flexible animals. The patron ghost of the house was the Bloody Baron. There were two notable heads of the house Horace Slughorn took the role twice (first leaving in 1981 and then taking the role again from 1997 until leaving before 2016), and Severus Snape. The emblematic animal of the house was a snake and the house's colours were green and silver. However, a Muggle-born student from that house was considered to be quite rare. Students of any blood status could be placed in the house. The founder highly valued and favoured pure-blood students and the Sorting Hat admitted that it could be a factor when being sorted. Examples of these included Draco Malfoy's gang, Merula Snyde's gang, Pansy Parkinson's gang and Tom Riddle's gang (which later became the Death Eaters). Many Slytherin students tended to clique together (often acquiring leaders) which further exemplified Slytherin's ambitious qualities. Those characteristics included cunning, resourcefulness, leadership, and ambition. In establishing the house, Salazar instructed the Sorting Hat to pick students who had a few particular characteristics he most valued. Slytherin was one of the four Houses at Hogwarts School of Witchcraft and Wizardry, founded by Salazar Slytherin.

Black family (exception of Sirius Black).

Harry potter sorting hat quiz for kids